In C, round() rounds x to the nearest integer. A halfway value moves away from zero, so round(1.5) is 2 and round(-1.5) is -2.
You pass one double. The result is still a double, such as 2.0, not an int. Include <math.h>.
Pass the number you want to round. Start with this call.
round(1.5);| Call | What it does |
|---|---|
round(1.5) | Rounds halfway away from zero and returns 2. |
Include <math.h>. On GCC, link with -lm. The result type is still double.
double round(double x);
float roundf(float x);
long double roundl(long double x);| Parameter | Description |
|---|---|
| x | Required. The double to round to the nearest integer. |
| Return Value | Description |
|---|---|
| double | The nearest integer value, stored as a double. Halfway cases go away from zero. |
Print a few everyday rounding results.
#include <math.h>
#include <stdio.h>
int main(void) {
printf("round(15.67) = %.1f\n", round(15.67));
printf("round(15.32) = %.1f\n", round(15.32));
printf("round(-2.3) = %.1f\n", round(-2.3));
return 0;
}round; link with -lm on GCC.15.67 is closer to 16.15.32 is closer to 15.-2.3 is closer to -2 than to -3.Exact .5 values round away from zero in C (round), unlike trunc.
#include <math.h>
#include <stdio.h>
int main(void) {
printf("round(2.5) = %.1f\n", round(2.5));
printf("round(-2.5) = %.1f\n", round(-2.5));
printf("trunc(2.5) = %.1f\n", trunc(2.5));
return 0;
}2.5 is tied → pick 3 (away from 0).-2.5 is tied → pick -3 (also away from 0).trunc would keep 2.0 by dropping the fraction.3.0, not an int.Round a price to the nearest whole currency unit for a simple display.
#include <math.h>
#include <stdio.h>
int main(void) {
double price = 19.49;
double rounded = round(price);
printf("price = %.2f\n", price);
printf("rounded = %.0f\n", rounded);
return 0;
}19.49 is closer to 19 than to 20.19.0 as a double.%.0f shows a whole number for display.Compute the sine of an angle in radians.
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